This proposal seeks support for research on the epidemiology of inhalant use and dependence, including incidence, determinants, comorbidity, and substance abuse service utilization in nationally representative samples of household residents. The proposed research focuses on the extent and magnitude of inhalant use/dependence among school dropouts, females of childbearing ages, ethnic minority groups, and children of drug-using parents. Analyses will be performed on public use data files from multiple waves of recent National Household Surveys on Drug Abuse and the National Comorbidity Survey. Inhalant abuse has been described as one of the most pervasive yet least recognized drug problems, particularly among adolescents. Current knowledge about inhalant use is based primarily on the prevalence of inhalant "use." This proposed study addresses the following specific aims (1) to examine the incidence and determinants of inhalant initiation, (2) to determine the pattern and determinants of inhalant use/dependence among youths, school dropouts, females of childbearing ages, ethnic minority groups, and children of drug users, (3) to identify subgroup variation in the developmental sequence of inhalant use to other illicit drug use (females, ethnic minority groups, and multiple or early-onset drug users), (4) to explore the natural course of inhalant dependence, subtypes of inhalant users, and symptom profiles of inhalant dependence, and (5) to examine comorbidity and substance abuse service utilization. The proposed analysis will provide estimates of incidence trends and the characteristics related to onset of inhalant use. The pattern and magnitude of inhalant use/dependence by special subgroups will be examined so that their needs for prevention or substance abuse services can be better served. Subgroups of inhalant users vulnerable for psychopathology and underserved users will also be identified. The information generated will be vital to policy makers in predicting the potential burden of inhalant use problems and planning service delivery. Gaps in our knowledge of the natural course of inhalant use will be specified for future research. [unreadable] [unreadable]